In the following reaction ' X ' is $\mathrm{CH}_{3}\left(\mathrm{CH}_{2}\right)_{4} \mathrm{CH}_{3} \xrightarrow[\text { HCl, } \Delta]{\text { Anhy. } \mathrm{AlCl}_{3}}{}_\text {major product} \mathrm{X}$

(A) $\mathrm{CH}_{3}\left(\mathrm{CH}_{2}\right)_{4} \mathrm{CH}_{2} \mathrm{Cl}$

(B) $\mathrm{Cl}-\mathrm{CH}_{2}-\left(\mathrm{CH}_{2}\right)_{4}-\mathrm{CH}_{2}-\mathrm{Cl}$

JEE Main · 2023 · 13 Apr 2023 · Shift 1 · Hydrocarbons

In the following reaction ' X ' is

CH_{3} (CH_{2})_{4} CH_{3} Anhy. AlCl_{3} HCl, Δ_{major product} X

(A) $CH_{3} (CH_{2})_{4} CH_{2} Cl$
(B) $Cl - CH_{2} - (CH_{2})_{4} - CH_{2} - Cl$
(C)(see structure)
✓ Correct
(D)(see structure)

Answer: (C)

Solution

In the presence of anhydrous aluminium chloride and a trace of hydrogen chloride on heating, straight-chain alkanes undergo skeletal isomerisation. The reaction proceeds through carbocations that rearrange towards more stable branched structures. n-Hexane is converted mainly to its monomethyl-branched isomer, 2-methylpentane,

(C H_{3})_{2} CH - C H_{2} - C H_{2} - C H_{3}

, which is the major product.

JEE Main · 2023 · 13 Apr 2023 · Shift 1 · Single correct option

Practise more: all JEE Main PYQs on Hydrocarbons →

More JEE Main questions on Hydrocarbons

Identify A in the following reaction.
JEE Main 2026View solution →
Given below are two statements :

Statement I : Benzene is nitrated to give nitrobenzene, which on further treatment with
$CH_{3} COCl / AlCl_{3}$ will give
JEE Main 2026View solution →
As compared with chlorocyclohexane, which of the following statements correctly apply to chlorobenzene?
A. The magnitude of negative charge is more on chlorine atoms
B. The $C - Cl$ bond has partial double bond character
C. $C - Cl$ bond is les …
JEE Main 2026View solution →
The cycloalkane ( X ) on bromination consumes one mole of bromine per mole of ( X ) and gives the product ( Y ) in which $C : Br$ ratio is $3 : 1$ . The percentage of bromine in the product $(Y)$ is
____ %. (Nearest integer)
(Given : Molar mass …
JEE Main 2026View solution →
The dibromo compound [P] (molecular formula: $C_{9} H_{10} Br_{2}$ ) when heated with excess sodamide followed by treatment with dilute HCl gives [Q]. On warming [Q] with mercuric sulphate and dilute sulphuric acid yield [R] which gives positive Iodoform t …
JEE Main 2026View solution →
But-2-yne and hydrogen (one mole each) are separately treated with (i) $Pd / C$ and (ii) $Na /$ liq. $NH_{3}$ to give the products X and Y respectively.

Identify the incorrect statements.
A. $X$ and $Y$ are stereoisomers.
B. Dipole moment of X …
JEE Main 2026View solution →